This invention relates to apparatus for mixing a gas and a liquid, and for dispensing the resultant solution. In some fields, especially the medical field, it is desirable to dissolve a gas in a liquid without loss of the gas and without contamination of the solution. One specific use for the apparatus is the dissolving of a radioactive gas such as xenon-133 in a liquid such as saline to provide a radioactive solution and provide for extraction of a portion of the solution for subsequent use such as tracering in medical analysis. For such applications, the dispenser should also provide radioactive shielding for protection of personnel handling the equipment.
One such apparatus is shown in U.S. Pat. No. 3,742,988. In this apparatus, a crushable ampule is positioned in a closed container which is charged with the saline. The ampule is crushed or broken by a lead screw positioned in a cap for the container to permit mixture of the gas and liquid. An inlet line provides for introducing the saline into the container, and an outlet line provides for withdrawing the solution.
This prior art device has a number of disadvantages. It is not well suited for use with small volumes, in the order of 5 to 6 cubic centimeters as compared to 30 cubic centimeters. The device requires crushing of the ampule within the container. Also, the gas is mixed with the liquid in the container rather than in the ampule, thereby lowering the concentration of the radioactive gas in the liquid and increasing the possibility of contamination.
In another prior art apparatus which has been in use for several years, the larger portion of an ampule is enclosed in plaster, a syringe cap is attached to the ampule neck by a rubber tube, a syringe is coupled to the interior of the rubber tube by a plastic line and a small needle through the syringe cap, and a larger needle with a valve at the outer end is inserted through the syringe cap into the ampule neck to break the ampule seal.
This prior art device also has disadvantages. The ampule neck often broke at the time the seal was broken or during subsequent use and there was considerable gas leakage. The unit was akward to assemble and handle, and time was required to initially seal the ampule in plaster.
Accordingly, it is an object of the present invention to provide a new and improved apparatus for mixing a gas and a liquid and for dispensing the resultant solution. A particular object is to provide such an apparatus which is especially well suited for handling small volumes, typically 5 to 6 cubic centimeters and less. Another object is to provide such an apparatus wherein the ampule is fully enclosed and protected in a housing and maintained intact, with the liquid being introduced into the ampule for mixing with the gas. An additional object is to provide such an apparatus incorporating a collar for clamping the ampule in place and a cap for sealing engagement with the ampule, with flow paths for gas and liquid within the housing and cap. Other objects, advantages, features and results will more fully appear in the course of the following description.